Many types of printing apparatus are capable of printing only on a single side of the recording medium. However, the desirability of saving paper (or other types of printing media) by printing on both sides is widely recognized. A variety of duplexing designs have previously been disclosed for reversing a side of the media facing the print region after a first side has been printed, in order to allow printing on the opposite side.
In some low-cost printers, as described in U.S. Pat. No. 7,561,823, a duplexing unit is provided as a removable auxiliary unit that the user can decide whether or not to purchase, according to his printing needs. If the user does purchase the auxiliary duplexing unit, he needs to install it himself, thus increasing the complexity of the setting up of the printing apparatus.
For permanently attached duplexing units it can be advantageous to make the inner portions of the media path accessible in order to facilitate the clearing of paper jams by the user. U.S. Pat. Nos. 4,825,245, 4,884,110, 6,564,019 and 7,536,133 have disclosed hinged duplexing units for electrostatic printers such as laser printers. Due to the configuration of such printers the duplexing unit was not located near a base of the unit. The hinges of the duplexing units as disclosed in these patents were configured to be horizontal (i.e. parallel to the base), so that the duplexing unit is configured to pivot upward or downward.
In a low-cost desktop printer, such as an inkjet printer, the printer is intended to sit on the user's desk or other flat surface that extends beyond the base of the printer. In addition, for a compact height printer having a C-shaped paper path (with the media input holder located below the media output holder), the duplexing unit is typically located very close to the base of the printer. For a duplexing unit located very close to the base of a desktop printer, a horizontal hinge configuration has disadvantages. If the hinge is located at the top of the duplexing unit, the duplexing unit would pivot upwards. However, since the user is typically taller than the desktop, the upwardly pivoted duplexing unit would obscure visibility and interfere with access to the media paths inside. Even if the user bent over so that his eyes were at desktop level, it would make it difficult to reach in and clear out paper jams between the upwardly pivoted duplexing unit and the desktop. If the hinge is located at the bottom of the duplexing unit, the duplexing unit would pivot downwards. However, if the duplexing unit is located very near the base of the printing apparatus, its pivoting motion would typically cause it to hit the desktop before opening all the way, again interfering with visibility and access to the media paths for clearing paper jams.
What is needed is a duplexing unit that does not require user installation, and that allows good visibility and access to media paths inside the printing apparatus in order to facilitate clearing out paper jams.